星际化学的复杂性增加：Sgr B2（N）中甲酸乙酯和正丙基氰的探测和化学模拟
Increased complexity in interstellar chemistry: Detection and chemical modeling of ethyl formate and n-propyl cyanide in Sgr B2(N)
摘要：
近年来，越来越复杂的有机分子被发现朝向银河系中心源人马座B2。我们希望探索星际化学在恒星形成区域中所能达到的复杂程度。我们用IRAM 30 m望远镜在3 mm范围内对热芯Sgr B2（N）和（M）进行了完整的线测量。我们在LTE近似下分析了这一频谱调查。我们同时模拟了所有已知分子的发射，这使我们能够寻找丰度较低，更复杂的分子。我们比较了推导出的柱密度与预测的耦合气相和颗粒表面化学代码。我们报告了在空间中首次检测到甲酸乙酯（C2 H5 OCHO）和正丙基氰（C3 H7 CN）对Sgr B2（N）。甲酸乙酯和正丙腈相对于H2的丰度估计分别为3.6e-9和1.0e-9。我们的化学建模表明，顺序，分段建设的乙基和正丙基氰化物从其组成的官能团在晶粒表面上是他们最有可能的形成路线。甲酸乙酯主要通过将CH 3添加到衍生自甲酸甲酯的官能团自由基上在晶粒上形成，尽管乙醇也可以是前体。在Sgr B2（N）中检测到两类复杂分子（酯类和烷基氰化物）的下一阶段复杂性，表明星际介质中可能存在其他类型分子的更大复杂性。【摘要】
英文摘要：
In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range. We analyzed this spectral survey in the LTE approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code. We report the first detection in space of ethyl formate (C2H5OCHO) and n-propyl cyanide (C3H7CN) toward Sgr B2(N). The abundances of ethyl formate and n-propyl cyanide relative to H2 are estimated to be 3.6e-9 and 1.0e-9, respectively. Our chemical modeling suggests that the sequential, piecewise construction of ethyl and n-propyl cyanide from their constituent functional groups on the grain surfaces is their most likely formation route. Ethyl formate is primarily formed on the grains by adding CH3 to functional-group radicals derived from methyl formate, although ethanol may also be a precursor. The detection in Sgr B2(N) of the next stage of complexity in two classes of complex molecule, esters and alkyl cyanides, suggests that greater complexity in other classes of molecule may be present in the interstellar medium. {Abridged}
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